1. Field of the Invention
The present invention relates to a terminal fitting that can be connected to a flat conductor and a method of connecting the terminal fitting to the flat conductor.
2. Description of the Related Art
Prior art flat conductors include flexible flat cables (FFC) and flexible print circuit boards (FPC). The prior art FFC includes a plurality of conductive paths arranged in parallel with one another and sandwiched between insulation sheets. The FFC is formed flexibly in the shape of a ribbon. A terminal fitting is connected to each conductive path of the FFC by embedding the conductive paths of the FFC in the insulation sheet or by tearing off a portion of the insulation sheet of the FFC to expose a section of the conductive paths.
The former method is called a through type method, and has an advantage of omitting the stage of tearing off the insulation sheet. This method is disclosed in Japanese Patent Application Laid-Open No. 50-100585, and is shown in FIG. 15A. In this prior art method, contact blades 2 are erected on both side edges of a terminal fitting 1. Both contact blades 2 pierce a conductive path 4 of an FFC 3 to bring cut end surfaces of the conductive path 4 into side surfaces of the contact blade 2.
However, in the above-described method, the FFC is liable to curve between the contact blades 2 when the contact blade 2 pierces through the conductive path 4, as shown in FIG. 15B. Therefore, there is a possibility that insufficient contact pressure is obtained between a cut surface 4A of the conductive path 4 and the side surfaces of the contact blade 2 or that only a part (corner) of an insulation sheet 5 is in contact with the side surfaces of the contact blade 2. Thus, the method does not produce a reliable electrical contact.
The present invention has been completed in view of the above-described situation. Thus, it is an object of the present invention to obtain a high contact pressure between a contact blade of a metal fitting of through type and a cut surface of a conductive path of a flat conductor.
The subject invention is directed to a terminal fitting for a flat conductor, and specifically a terminal fitting that can be connected to a terminal of a flat conductor in which a conductive path is embedded in an insulation layer. The terminal fitting comprises a base plate disposed on and fixed to a surface of a disposing position of the conductive path. At least one contact blade projects from the base plate and pierces through the conductive path. The terminal fitting further comprises a pressing plate that presses the flat conductor toward the base plate. Thus the flat conductor is sandwiched between the pressing plate and the base plate.
Contact blades preferably are erected on both side edges of the base plate, such that the contact blade at the one side edge confronts the contact blade at the other side edge. In this embodiment, the pressing plate is capable of penetrating into a space between the contact blades that project up from the side edges of the base plate. More particularly, the pressing plate has opposed side surfaces that define a width for the pressing plate. The width is selected such that the side surfaces of the pressing plate slide in contact with inner surfaces of the contact blades that project up from the side edges of the base plate.
The pressing plate preferably is crimped to the flat conductor and remains on the flat conductor, with the flat conductor sandwiched between the base plate and the pressing plate.
A projection may be formed on a surface of the base plate and/or a surface of the pressing plate that confronts the surface of the base plate.
The terminal fitting may further comprise a piercing piece that can be pierced through the conductive path. The piercing piece is formed by bending a front end of the pressing plate in a direction in which the flat conductor is inserted into a space between the base plate and the pressing plate.
The invention also is directed to a method of connecting a terminal fitting to a terminal of a flat conductor in which a conductive path is embedded in an insulation layer. The method comprises projecting a contact blade from a base plate of the terminal fitting. The method continues by piercing the contact blade through the conductive path, with the base plate in contact with a surface of the terminal of the flat conductor. The method then includes pressing the flat conductor against the base plate, with the pressing plate in contact with an opposite surface of the flat conductor.
The contact blade pierces the conductive plate, and the pressing plate presses the flat conductor against the base plate. The conductive path is compressed in a thickness direction. Therefore, cut surfaces of the conductive path project widthwise and contact the contact blades at a high pressure. Consequently, it is possible to obtain a stable electrical performance.
The pressing plate penetrates into the space between the contact blades at both side edges of the base plate, with the pressing plate in sliding contact with the contact blades. Therefore, cut surfaces of the conductive path are adjusted to be straight in the entire width, are compressed vertically and can be brought into contact with the contact blades reliably.
The pressing plate remains on the flat conductor after the terminal fitting is connected to the terminal of the flat conductor. Thus, the pressing plate keeps compressing the conductive path.
The projected portion is pressed against the conductive path. Thus, it is possible to effectively project the cut surfaces of the conductive path widthwise. Further, the projected portion serves as a means for catching the flat conductor, thus firmly holding the flat conductor in resistance to a tensile force applied thereto.
The piercing piece pierces the conductive path, thus hooking the flat conductor and firmly holding the flat conductor in resistance to a tensile force applied thereto and increasing the contact area.